Strapping machines are known for securing straps around loads. In a typical arrangement, strap material is fed from dispenser into a strapping machine. The strap is fed through a feed head and a sealing head and into a strap chute. Once the strap is conveyed beyond the feed head, it is “pushed” through the strap chute that forms an archway or like path around the load.
The strap continues to be “pushed” until the lead end of the strap returns to the sealing head. Once the strap returns to the sealing head, the lead end is gripped in a gripper, and overlapping course of strap material are sealed to one another, as by welding, to form the strap joint. The strap is then severed downstream of the strap joint and the load removed from the strapping machine. A subsequent lead end is then ready to be pushed through the strap chute to strap the next load.
In an effort to reduce the costs associated with such packaging or bundling operations, strap material has been made thinner as it has been made stronger. While this has resulted in material cost savings, the thinner strap tends to curl to a greater extent than thicker strap, and has less structure or is less rigid than thicker strap. As such, strap misfeeds can occur.
Efforts have been made to increase the column strength of the thinner strap. One such strap, disclosed in Pearson, US Publication 2008/0201911, and commonly assigned with the present application includes semi-circular ribs formed longitudinally along the strap to increase the column stiffness of the strap. While this ribbed strap exhibits increased column stiffness, the ribs increase the effective cross-sectional area of the strap which requires additional space when the strap is wound onto a reel. As such, equal size reels of flat and ribbed strap will carry less ribbed strap. Moreover, additional manufacturing steps are required to form the ribs in the strap and to assure that the edges of the strap remain flat for proper functioning of the strapping machine in which it is used.
Another type of strap with increased column stiffness includes a flat strap with a slit or cut formed into a portion of the thickness of the strap, longitudinally along the strap, and is illustrated in FIGS. 7A and 7B. The strap is then bent so that the strap is folded along the length of the strap. Such a strap has the advantages of the ribbed strap, that is, increased column strength with reduced material, but has the further advantage of not increasing the effective cross-sectional area of the strap when the strap is stored flat. Such a strap can also be formed with two longitudinal bends. An example of such a strap is disclosed in copending, commonly assigned, Enriquez, U.S. patent application Ser. No. 13/047,482, the disclosure of which is incorporated herein by reference.
There has, however, not been a device to conform the flat strap to the bent strap configuration.
Accordingly, there is a need for a device to conform or form the bent strap configuration for use in a strapping machine. Desirably, such a device can be used with known strapping machines. More desirably, such a device can be installed in or made part of known strapping machines. More desirably still, such a device can be manufactured as part of a modular strapping head used in known strapping machines.